The present disclosure generally relates to semiconductor structures, and particularly to semiconductor structures having a semiconductor-oxide-containing gate dielectric and a high dielectric constant (high-k) gate dielectric, and methods of manufacturing the same.
Many types of semiconductor devices can be employed in a semiconductor chip to provide various functionalities. Typically, some devices are optimized for performance, and some other devices are optimized for low power consumption. One of the methods commonly employed to provide different types of semiconductor devices is to employ multiple types of gate dielectrics. For example, a semiconductor-oxide-containing gate dielectric and a high-k gate dielectric can be employed on a same semiconductor substrate to provide different types of semiconductor devices.
A simple integration scheme for enabling semiconductor-oxide-containing gate dielectrics and high-k gate dielectrics on a same semiconductor substrate can employ a step of forming semiconductor-oxide-containing gate dielectrics prior to formation of source and drain regions in combination with a step of removing a subset of the semiconductor-oxide-containing gate dielectrics in regions where formation of high-k gate dielectrics is desired. However, this integration scheme results in damages and/or undercut to the semiconductor-oxide-containing gate dielectrics if employed in conjunction with any anisotropic etch that extends the depth of gate cavities. While extension of the gate cavities is desirable for the purpose of increasing the on-current of field effect transistors, degradation of the semiconductor-oxide-containing gate dielectrics should be avoided to maintain device performance. Thus, an integration scheme is desired for concurrently providing undamaged semiconductor-oxide-containing gate dielectrics and vertically extended gate electrodes.